Organozinc Pivalate Reagents: Segregation, Solubility, Stabilization, and Structural Insights
Organozinc Pivalate Reagents: Segregation, Solubility, Stabilization, and Structural Insights
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DOI：
10.1002/anie.201309841
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发表时间：
2014-03-03
影响因子：
16.6
通讯作者：
Schnegelsberg, Christoph
中科院分区：
文献类型：
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作者：
Hernan-Gomez, Alberto;Herd, Emma;Schnegelsberg, Christoph
在盐支撑的有机金属试剂中，RZnOPivMg(OPiv)XnLiCl （OPiv=pivalate； R=aryl； X=Cl, Br， I）脱颖而出，因为除了它们在根石交叉偶联反应中有效外，它们比传统的有机金属化合物更能抵抗潮湿空气的攻击。在这里，合成、耦合应用、x射线晶体学研究、核磁共振（包括DOSY）研究和ESI质谱研究的结合提供了这些私人试剂的详细信息。在[D-8]THF溶液中，这些试剂以分离的Me(p-C6H4)ZnCl和Mg(OPiv)(2)存在。空气暴露试验和x射线晶体学研究表明，Mg(OPiv)(2)通过吸附H2O污染物增强芳基锌的空气稳定性。Me(p-C6H4)ZnX（其中X=不同的盐）与4-溴苯甲醚的偶联反应突出了Mg（OPiv）存在的重要性(2)。LiCl在这些多组分混合物中的作用由[(THF)(2)Li-2(Cl)(2)(OPiv)(2)Zn]的分子结构提供。
The pivalates RZnOPivMg(OPiv)XnLiCl (OPiv=pivalate; R=aryl; X=Cl, Br, I) stand out amongst salt-supported organometallic reagents, because apart from their effectiveness in Negishi cross-coupling reactions, they show more resistance to attack by moist air than conventional organometallic compounds. Herein a combination of synthesis, coupling applications, X-ray crystallographic studies, NMR (including DOSY) studies, and ESI mass spectrometric studies provide details of these pivalate reagents in their own right. A p-tolyl case system shows that in [D-8]THF solution these reagents exist as separated Me(p-C6H4)ZnCl and Mg(OPiv)(2) species. Air exposure tests and X-ray crystallographic studies indicate that Mg(OPiv)(2) enhances the air stability of aryl zinc species by sequestering H2O contaminants. Coupling reactions of Me(p-C6H4)ZnX (where X=different salts) with 4-bromoanisole highlight the importance of the presence of Mg(OPiv)(2). Insight into the role of LiCl in these multicomponent mixtures is provided by the molecular structure of [(THF)(2)Li-2(Cl)(2)(OPiv)(2)Zn].